The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it may be described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
Hydrides, compounds in which metals or metalloids are bound directly to hydrogen, are relatively energetic molecules with a large variety of known and developing applications in chemistry and energy technology. Such applications include uses as reducing agents, hydrogenation catalysts, desiccants, potent bases, components in rechargeable batteries, and potentially as solid hydrogen storage vehicles in fuel cell technology.
Elemental nanoparticles, particles of composed of elements in elemental form (e.g. not ionized, covalently bonded to other elements, etc) with a dimension less than 100 nm, have unique physical, chemical, electrical, magnetic, optical, and other properties in comparison to their corresponding bulk elements. As such they are in use or under development in fields such as chemistry, medicine, energy, and advanced electronics, among others.
Synthetic methods for elemental nanoparticles are typically characterized as being “top-down” or “bottom-up” and comprise a variety of chemical, physical, and even biological approaches. Top-down techniques involve the physical breakdown of macroscale metallic particles, using a variety of energy inputs, into nanoscale particles. Bottom-up methods involve the formation of nanoparticles from isolated atoms, molecules, or clusters.
Physical force methods for top-down elemental nanoparticle synthesis have included milling of macroscale metal particles, laser ablation of macroscale metals, and spark erosion of macroscale metals. Chemical approaches to bottom-up synthesis commonly involve the reduction of metal salt to elemental metal with nucleation seed particles or self-nucleation and growth into metal nanoparticles.
While each of these methods can be effective in certain circumstances, each also has disadvantages or situational inapplicability. Direct milling methods can be limited in the size of particles obtainable (production of particles smaller than ˜20 nm is often difficult) and can lead to loss of control of the stoichiometric ratios of alloys, for example. Other physical methods can be expensive or otherwise unamenable to industrial scale. On the other hand, chemical reduction techniques can fail, for example in situations where precursor cations are resistant to chemical reduction. Mn(II) for example is virtually impervious to in situ chemical reduction, making this approach essentially non-viable for the synthesis of manganese nanoparticles.
A family of synthetic methodologies, capable of producing high-purity elemental nanoparticles having a single element or more than one element, would be useful.